To let everyone know some knowledge of touch screen Character LCD Module

Touch screen working principle and information transmission medium, the touch screen is divided into resistive, acoustic pulse recognition (APR), surface acoustic wave (SAW), surface acoustic wave (SAW), capacitive and infrared / optical. Each type of touch screen has its own advantages and disadvantages, to understand the kind of touch screen apply to such a case, the key is to understand the working principle and characteristics of each type of touch screen technology.
Resistance: from the promotion and application of the resistive touch screen is the dominant touch technology. It is composed by a glass panel, iridium-tin oxide (ITO) resistor coating, and a retaining plate with a conductive coating, and total silver lines along the edges. Between the two layers separated by insulating dots. Touch screen, shield bending in contact with the coating on the glass. The controller can choose to drive the retaining plate of the glass layer and the +5 V and the read voltage generated from the retaining plate and the glass layer, in accordance with the pressure drop is measured layer to determine the X and Y coordinates. The technique requires a four-wire lines mentioned earlier, this is known as 4-wire resistive touch screen technology. Due to continuous bending of the retaining plate, resulting in a tiny crack in the ITO coating film. Make 4-wire resistive touch screen technology linearity and accuracy variation, environmental change will cause the accuracy of the drift. Has been continuous improvement of 5 -, 6 -, 7 - and 8-wire resistive touch screen to eliminate these effects.
Acoustic Pulse Recognition (APR) formula: APR by a glass display coating or other hard substrates composed of four piezoelectric sensor mounted on the back. The sensor is installed in the visible region of the two angle by a bending of the cable connected to the control card. When the user touches the screen, drag your finger or stylus and glass collision or friction, and thus a sound wave. Radiation away from the contact point pass to the sensor generates an electrical signal in proportion to the sound waves. These signals are amplified in the control card, and then converted to a digital data stream. Compare data and the sound list stored in advance to determine the position where the touch. APR is designed to be able to eliminate the environmental impact and external sound, because the sound of these factors and stored list does not match.Character LCD Display
Surface acoustic wave (SAW) of formula: SAW touch screen for the X and Y axes by a glass coating of the sending and receiving piezoelectric transducers. The controller sends an electrical signal to the transmission sensor and the ultrasonic signal into the inner surface of the glass. Reflector array, these waves covering the entire touch screen. The opposite side of the reflector collection and control of these waves to the receiving sensor, and converts them into electrical signals. This process is repeated for each axis. Absorption when the user touches a part of the wave propagation. The received signal corresponding to the X and Y coordinates with the stored digital maps compared in order to identify changes in the calculated coordinates.
Capacitive: capacitive touch screen technology can be further subdivided into surface capacitive and projected capacitive. Surface capacitive technology is on the glass panel coated with the same conductor. Around the edge of the panel electrode is evenly distributed throughout the conductive layer of low voltage, to create the same electric field. Touch will get from each corner of the current. The controller measures the ratio of the currents obtained from each corner, thereby calculating the position where the touch.
Projected capacitive touch screen by the the sensor grid fine line between the two glass protective layer. The member can be placed behind the user to install the material, including riot 18 mm thick glass. Touch formed between the finger and the sensor capacitance. Grid from the sensor to change the electrical characteristics of the touch position can be calculated.TFT Lcd Modules
IR / optical: high-resolution infrared (IR) technology uses a small box around the display, with surface-mounted LED side light receptors, infrared transparent border hidden in the back. The controller continuous transmission LED, in order to build an infrared light scanning grid. Bouquet of each axis or more beams of infrared light barrier will touch, and thus determine the corresponding X, Y coordinates.